Semiempirical molecular orbital method for estimating the hyperconjugative contribution to .beta.-secondary deuterium isotope effects

Abstract

sealed, and immersed in a thermoregulated oil bath at 74.0 f 0.1". constants were: in isooctane, k = 1.77 x sec-I and inThe tubes were removed at various time intervals, quenched in ice, paraffin oil. k = 0.91 x sec-'.. read in the spectrometer, and reimmersed in the bath: All rate plots were linear for three half-lives, and the rate constants were obtained by a least-squares treatment2' of the experimental data. The rate Acknowledgment. We wish to express our appreciation to the National Science Foundation and the U. S.Army Research Office, Durham, for financial support of this work. Abstract:A semiempirical equation is derived to connect w-SCF molecular orbital wave functions and eigenvalues with the hyperconjugative contribution to $-secondary deuterium isotope effects. The results of the application of this equation to a number of hydrocarbon systems are discussed. econdary deuterium kinetic isotope effects have been tems," W. A. Benjamin, Inc., New York, N. Y., 1966. (9) L. Salem, "The Molecular Orbital Theory of Conjugated Sys-Koenig, Wolf Hyperconjugative Contribution to Secondary D Effects -, , . ,, , . 90, 7014 (1968). (12) T. Koenig, ibid., 91, 2558 (1969).

"Normal" temperature-induced helix-coil transition of poly(.gamma.-N-carbobenzoxy-L-.alpha.,.gamma.-diaminobutyric acid) in mixed organic solvents

“…Reaction of oxepin-benzene oxide systems with nucleophiles appears to be a useful route for the nonenzymatic synthesis of heteroatom-substituted 1,3-cyclohexadienes.18 (18) cis-and trans-5,6-dihydroxy-l,3-cyclohexadiene Received July 14,1969 A "Normal" Temperature-Induced Helix-Coil Transition of Polv-7-N-carbobenzoxy-L-a,7-diaminobutyric Acid in Mixed Organic Solvents1…”